OLAP Cache: Does It Have to Be Configured?

by Ned Falk, Senior Education Consultant, SAP

April 1, 2004

One of the differences between the BW 2.0 system and versions 3.0B and above is the way that OLAP queries are cached. The author explains the added features and global cache of newer versions of BW. He describes the cache configuration settings of BW version 3.x and their impact on system performance.

The OLAP (online analytical processing) cache is a repository for query result sets that provides users with quicker access to the data. It is populated after a query is run for the first time, and it provides performance improvements for subsequent executions of the same query. Report-specific data is retained in the cache on the application or the database server separately from the usual InfoProvider or aggregate where it would normally be stored.

In BW 2.0, the OLAP cache was not managed, but starting with BW 3.0B, it does require management along with configuration. With the release of BW versions 3.1 and later, additional configuration settings are possible that support added features. I will explain how to configure the cache as well as which options you may choose in BW 3.0B systems and in later releases. I will also describe issues you’ll face if your system taps into the global OLAP cache.

Before the release of BW 3.0, the system basically worked as shown in Figure 1. When a user executed a query, the data supporting the report was sent to the application server where the calculations were processed and cached. The completed report was then sent to the user’s PC, laptop, or handheld device, known collectively as the presentation server. As the user navigated, the cache of data involved would increase. In some cases, such as when prior requests had already been extracted from the database, the navigation step could be accessed directly from the cache on the application server.

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Ned Falk

Ned Falk is a senior education consultant at SAP. In prior positions, he implemented many ERP solutions, including SAP R/3. While at SAP, he initially focused on logistics. Now he focuses on SAP HANA, SAP BW (formerly SAP NetWeaver BW), SAP CRM, and the integration of SAP BW and SAP BusinessObjects tools. You can meet him in person when he teaches SAP HANA, SAP BW, or SAP CRM classes from the Atlanta SAP office, or in a virtual training class over the web. If you need an SAP education plan for SAP HANA, SAP BW, BusinessObjects, or SAP CRM, you may contact Ned via email.